In the U.S. the relative risk of end-stage renal disease (ESRD) is about fourfold higher for blacks than whites. Blacks represent an increasing proportion of patients maintained with renal replacement therapy. The number of renal transplantations increased two-fold in the past decade for both blacks and whites. However, as compared with whites, there are few studies of renal transplantation among blacks. We propose to analyze data from the USRDS to examine: Trends of renal transplantation as the treatment modality for ESRD" black and white comparison. As compared with whites, a smaller percentage of black patients on dialysis have undergone renal transplantation. The secular trends of this gap from 1977 to 1990 and in three times periods (1977-1982, 1983-1986, and 1987-1990_ will be examined. Secular trends of some demographic characteristics such as age, sex, and primary diseases causing ESRD, will also examined to see if they account for these racial trend differences. HLA typing and matching in blacks. In the U.S. blacks wait almost twice as long for a first transplant as do whites. Sine the HLA matching is heavily weighted as a criterion for kidney allocation, the impact of HLA frequency differences between races will be examined. Based on these data, a computer simulation will be performed to estimate the racial differences in obtaining various degrees of HLA matching for various recipient pool sizes. These analyses will permit us to further understand the effect of race on access to donor kidneys in renal transplantation. Outcome of renal transplantation in blacks. The role that both donor and recipient race plays in the success of a kidney transplant has been the subject of considerable debate. In this study the early graft function (early post transplant dialysis and rejection) as well as short- and long-term graft survival will be compared between blacks and whites. The effects of the following factors on racial differences in outcome will be examined: center effects, HLA matching, immunosuppression regimens, primary diseases causing ESRD, sensitization, blood transfusion, kidney ischemia time, donor and recipient sex and age. Effect of HLA matching on graft survival in blacks. The impact of HLA matching on graft survival in blacks will be investigated and compared to whites. Using proportional hazards modelling several questions will be investigated: Whether there is an association between HLA matching and graft survival in blacks and whether the impact of HLA matching is the same for blacks as for whites. Whether the impact of HLA matching as characterized by the number of mismatches determines a graded or a threshold effect on graft survival. Finally, which or in what kinds of combinations of A, B, and DR mismatches would better predict graft outcomes in blacks.